1. Field of the Invention
The present invention relates generally to a model gun with trajectory control function, and more particularly to an improvement in a model gun having trajectory control function in which a spherical sham bullet is temporarily put in a bullet holding portion provided just at the back of a barrel and then shot off through the barrel with gas pressure and the trajectory of the spherical sham bullet is controllable.
2. Description of the Prior Art
There has been proposed a model gun often called an air soft gun in which a bullet holding portion is provided just at the back of a barrel for holding temporarily a spherical sham bullet and the spherical sham bullet put temporarily in the bullet holding portion is shot off through the barrel with gas pressure supplied into the bullet holding portion. As for such a model gun as often called the air soft gun, there has been further proposed to extend the range of the spherical sham bullet shot with the gas pressure, without increasing the power of the spherical sham bullet, so as to raise the commercial value of the model gun.
In the case of the previously proposed model gun in which it is intended to extend the range of a spherical sham bullet shot off through a barrel with gas pressure, as shown in, for example, Japanese patent application published after examination under publication number 7-21398, the barrel is provided to be accompanied, at the back thereof, with a bullet shooting portion at which a spherical sham bullet is temporarily held, and a partitioned upper inner surface of a part of the barrel is formed with friction material so as to project slightly downward with the coefficient of friction thereof higher than that of a partitioned lower inner surface of the part of the barrel which is opposite to the partitioned upper inner surface.
With the arrangement thus proposed, the amount of the downward projection of the partitioned upper inner surface is adjusted by a friction adjusting mechanism which works in response to the operation of a control handle, so that both of the partitioned upper and lower inner surfaces of the barrel come into contact with the spherical sham bullet which passes through the barrel after shooting from the bullet shooting portion. The spherical sham bullet with which both of the partitioned upper and lower inner surfaces of the barrel come into contact is given a rotation in such a rotating direction as to cause the spherical sham bullet to be subjected to dynamic lift with its forward movement due to a difference between the friction arising between the partitioned upper inner surface of the barrel and the spherical sham bullet and the friction arising between the partitioned lower inner surface of the barrel and the sham bullet. Consequently, the range of the spherical sham bullet shot off through the barrel can be extended without increasing its power.
The rotation of the spherical sham bullet with which the spherical sham bullet is subjected to the dynamic lift with its forward movement is such a rotation as to move upward the front end of the spherical sham bullet moving forward in the right or left side view in the direction perpendicular to the forward movement of the spherical sham bullet. This rotation of the spherical sham bullet is referred to as an upward rotation, hereinafter.
In the model gun in which it is intended to extend the range of the spherical sham bullet shot off through the barrel, the upward rotation of the spherical sham bullet passing through the barrel is caused under a condition where the friction arising between the partitioned upper inner surface of the barrel and the spherical sham bullet passing through the barrel after shooting is arranged to be larger than the friction arising between the partitioned lower inner surface of the barrel and the spherical sham bullet passing through the barrel after shooting.
In such a model gun as aforementioned in which friction material is provided in a barrel for forming a partitioned upper inner surface of the barrel projecting slightly downward and the amount of the downward projection of the partitioned upper inner surface of the barrel is adjusted by a friction adjusting mechanism which works in response to the operation of a control handle, the friction material which forms the partitioned upper inner surface of the barrel projecting slightly downward is operative to press the spherical sham bullet passing through the partitioned upper inner surface of the barrel downward to a partitioned lower inner surface of the barrel and therefore the spherical sham bullet having passed through the partitioned upper inner surface of the barrel moves forward to a muzzle provided on the barrel along a path deviated slightly downward from a longitudinal axis line in the barrel.
Accordingly, the spherical sham bullet having passed through the partitioned upper inner surface of the barrel is put in a condition where a space is formed between an upper inner surface of the barrel and the spherical sham bullet and gas pressure with which the spherical sham bullet has been shot goes through the space forward to the muzzle. The gas pressure which goes through the space formed between the upper inner surface of the barrel and the spherical sham bullet from the rear to the front of the spherical sham bullet is undesirably operative to reduce the upward rotation of the spherical sham bullet which is given to the spherical sham bullet by the friction material which forms the partitioned upper inner surface of the barrel projecting slightly downward. As a result, the dynamic lift exerted on the spherical sham bullet with the upward rotation of the latter is so reduced as not to extend efficiently the range of the spherical sham bullet shot off through the barrel.
Further, under the structural arrangement in which the friction material is provided in the barrel for forming the partitioned upper inner surface of the barrel projecting slightly downward and the friction adjusting mechanism which works in response to the operation of the control handle is also provided for adjusting the amount of the downward projection of the partitioned upper inner surface of the barrel, the barrel is required to be subjected to a drilling process for forming thereon an opening through which the friction material is inserted into the barrel to form the partitioned upper inner surface of the barrel, and in addition, since the friction adjusting mechanism which comprises, for example, a cam member, a press member and so on for controlling the amount of projection of the friction material and the control handle accompanied with the friction adjusting mechanism are provided on the barrel which is provided with the opening through the drilling process, the whole construction containing the barrel comes undesirably to be complicated to use a large number of parts and to increase the cost of production.